CS235090B2 - Herbicide or/and plant growth regulation preparation and method of its effective component production - Google Patents

Description

The present invention relates to a herbicidal and / or plant growth regulating composition comprising, as active ingredient, novel derivatives of α- (pyridyl-2-oxyphenoxy) propionic acid. The following is presented

The invention also relates to a process for the preparation of these novel β (pyridyl-2-oxyphenoxy) propionic acid derivatives.

New compounds of formula I have been found

<s in which

X is hydrogen or halogen,

R 1 is hydrogen or C 1 -C 6 alkyl,

R 6 represents a C 1 -C 6 alkyl group, a C 3 -C 4 alkenyl group or a phenyl group, or

R 1 and R 2 together are tetramethylene or pentamethylene, which have herbicidal properties and further have the ability to control plant growth.

Accordingly, the present invention provides a herbicidal and / or plant growth regulating agent, characterized in that it contains at least one α- (pyridyl-2-oxyphenoxy) propionic acid derivative of the formula I as active ingredient.

An alkyl group refers to the following groups according to the number of carbon atoms listed:

methyl, ethyl, propyl, butyl, pentyl, hexyl and their isomers, for example isopropyl, isobutyl, sec-butyl, etc. Alkenyl is, for example, 1-propenyl, allyl, 1-butenyl, 2-butenyl, halogeno, etc. Halogen here and in the rest is understood to mean fluorine, chlorine, bromine or iodine, preferably chlorine or bromine, especially chlorine.

with an equimolar amount of the oxime of formula III

The compounds of formula (I) are stable oils, resins or solids at room temperature and are characterized by very valuable herbicidal properties and also the ability to control plant growth. Accordingly, these compounds can be advantageously used in the agricultural or related fields to desired effect on plant growth and / or to control weeds.

Preferred groups of compounds of formula (I) are those in which X is chlorine, bromine or also hydrogen, and R 1 and R 2 are as defined in formula I.

Further preferred are those compounds of formula I wherein R 1 is hydrogen or C 1 -C 6 alkyl and R 2 is C 1 -C 6 alkyl and X is as defined in Formula I.

Particularly preferred are the following individual compounds:

α- [4- (3-chloro-5-trifluoromethylpyridyl-2-oxy) phenoxy] propionic acid acetonoxime ester, α- [4- (3-chloro-5-trifluoromethylpyridyl-2-oxy) phenoxy] propionic acid methyl ethyl ketone oxime ester, α- [4- (3-Chloro-5-trifluoromethyl-pyridyl-2-oxy) -phenoxy] -propionic acid diethyl ketone oxime ester.

The novel α- (pyridyl-2-oxyphenoxy) propionic acid derivatives of the general formula I can be prepared according to the following known methods, wherein in formulas II to V, X, R 1 and R 2 have the meanings given under formula I, Hal and Hal " a halogen atom, preferably chlorine or bromine, and M represents hydrogen or preferably an alkali metal or alkaline earth metal cation, in particular potassium or sodium cation.

According to the invention, the active compounds of the formula I are prepared by reacting in an organic solvent which is inert to the reactants at atmospheric pressure and at a temperature between -5 ° C and 200 ° C and optionally in the presence of an equimolar amount of inorganic or organic bases as acid binding agents, acid halide of formula II

X is as defined above, and Hal is a halogen atom,

in which

R1 and R2 are as defined above.

Another method for the preparation of compounds of formula (I) consists in reacting a compound of formula (IV)

f / l / J in which

X and M are as defined above, with the α-halopropionic acid oxime ester of formula (V)

CH,

I ³

COO-N = C

i I

in which

НаГ, Ri and R? are as defined above.

Finally, compounds of formula I are also obtained by reaction of 2-halo-5-trifluoromethylpyridine of formula VI

in which

X and Hal have the meanings given above, with the metal salt of the hydroquinone ether with the oximester of lactic acid of the general formula VII

сн _ъ

ОСН-СООЫ-С (vid

R <~ \ \

/

in which

M, R 1 and R 2 have the meanings given above.

In the above formulas, R1, Ra and X have the meanings given in formula I, Hal is a halogen atom, preferably chlorine or bromine, while M is hydrogen or an alkali or alkaline earth metal cation.

These reactions are carried out in organic solvents which are inert to the reactants, preferably in the presence of acid binding agents. Suitable acid-binding agents are organic and inorganic bases, for example tertiary amines such as trialkylamine (trimethylamine, triethylamine, tripropylamine etc., pyridine and pyridine bases (4-dimethylaminopyridine, 4-pyrrolidylaminopyridine etc.), oxides and hydroxides, alkoxides, alkali metal and alkaline earth metal carbonates and bicarbonates (potassium hydroxide, sodium hydroxide, sodium carbonate, etc.), as well as alkali metal salts of carboxylic acids (sodium acetate, etc .;

In most cases, the resulting hydrogen halide can be expelled from the reaction mixture by introducing an inert gas, such as nitrogen, or adsorbed onto a molecular sieve (pore size 0.3-0.5 nm).

All reactions are carried out in the presence of solvents or diluents inert to the reactants. Suitable aromatic and aliphatic hydrocarbons are, for example, benzene, toluene, xylenes, petroleum ether, cyclohexane, n-hexane; halogenated hydrocarbons such as chlorobenzene, methylene chloride, ethylene chloride, chloroform, carbon tetrachloride, tetrachlorethylene; alcohols, especially aliphatic alcohols such as methanol, ethanol, propanol, butanol; ethers and ether compounds such as dialkyl ethers (diethyl ether, diisopropyl ether, tert-butyl methyl ether, etc.), anisole, dioxane, tetrahydrofuran; nitriles such as acetonitrile, propionitrile, Ν, Ν-dialkylated amides such as dimethylformamide; dimethylsulfoxide; ketones such as acetone, diethyl ketone, methyl ethyl ketone, and mixtures of such solvents with each other. In some cases, one of the reactants may also itself serve as a solvent.

The reaction temperatures are usually between -5 and +200 ° C, preferably between 0 and 100 ° C, the reaction time depending on the reaction temperature and solvent chosen being from several minutes to several days. Generally, the reactions are carried out at atmospheric pressure or at a slight positive pressure. The presence of a reaction catalyst such as tetraalkylammonium chloride, potassium iodide and / or crown ether may be preferred.

The present invention also provides a process for the preparation of compounds of formula (I).

The starting materials of the formulas II to VII are known or can be prepared by methods known per se.

Substituted acid halides of formula II can be prepared, for example, by reacting a compound of formula VIII

HO O-CH-COOCH _h with a trifluoromethylpyridyl derivative of the general formula IX

X

(IX) wherein

X is as defined above.

Cleavage of the hydrochloric acid yields the intermediate of the general formula. X

in which

X is as defined above, whose ester group is saponified to a carboxyl group in a conventional manner, for example in an alkaline medium, and then converted, for example, by treatment with a suitable halogenating agent, such as SOCl2, to the acid halide of formula II. In formulas IX and X, X has the meanings given under formula I.

The compounds of formula X exhibit herbicidal activity.

The compound of formula VIII is available by reacting hydroquinone with 2-chloropropionic acid methyl ester in the presence of a base.

Substituted trifluoromethylpyridyloxy-p-hydroxyphenyl ethers of formula IV may be prepared according to the teachings of Belgian Patent Specification 862 325 and DOS No. 2,847,662 or 2,732,846.

The compounds of the formula I each have one asymmetric carbon atom C ^x in the adjacent position to the methyl group of the propionic ester.

In the synthesis, the active compounds of the formula I are generally formed as a racemic mixture and can be resolved into their optical antipodes in the usual manner, for example by fractional crystallization. On the other hand, it is also possible to synthesize optically pure compounds of formula (I) when starting from optically pure 2-halopropionic acid. The optical antipodes of formula I have a different biocidal effect, the D-form being more herbicidally effective.

Irrespective of said isomerism, unsymmetrically substituted (R 1 + R 2) active compounds of the formula I may be present in the syn- or anti-form.

If the deliberate synthesis is not carried out in order to isolate the pure isomers, the product of the formula I is always obtained in the form of a mixture of these possible isomeric forms.

It has previously been known that certain carboxylic acid oximesters can be used as herbicides (cf. European Patent Applications Nos. 2,246 and 3,114, and U.S. Patent 4,200,587), the herbicidal activity of these compounds, particularly against difficult to control however, weeds are not always satisfactory.

It has now surprisingly been found that the trifluoromethylated novel pyridyloxy derivatives of the formula I according to the present invention have a better herbicidal effect than the above compounds and can be used as weed control agents in pre-emergence and post-emergence treatments.

The active compounds of the formula I according to the invention and the herbicidal compositions containing them as active ingredient are particularly suitable for the selective control of difficult-to-control grass weeds in crops of crop plants, in particular in dicotyledonous crop plants such as soybeans and all cultivated legumes, cotton, sugar beet, sunflower, rape and other cruciferous species (BrassicaeaJ. They may also be used in perennial crops such as vines, fruit trees (apple, pear, peach, apricot), citrus, as well as rubber plantations or coconut palms Thus, the compounds of the invention are well tolerated by many crop plants and are very effective against weeds.

In addition, certain active compounds according to the invention also have the ability to favorably control the growth of plants (inhibit growth) in a suitable application rate. In particular, these substances also inhibit the growth of dicotyledonous plants. Examples of uses of the compounds of the invention that are useful include, for example, a reduction in vegetative growth in soybeans and similar legumes, resulting in increased harvesting of the culture. furthermore, suppressing undesirable shoot growth in tobacco whose main shoot has been trimmed, resulting in the formation of larger and more beautiful leaves, or suppressing the growth of dicotyledonous plants such as fruit trees, ornamental trees, shrubs and shrubbery to save trimming work.

The novel compounds of the present invention are of low toxicity to warm-blooded animals and their application causes no problems. The application rate is generally between 0.005 and 5 kg of active ingredient per ha, preferably between 0.05 and 2 kg of active ingredient per ha.

The active compounds of the formula I have a pronounced herbicidal action with low selectivity even in low rates of application in crops of useful plants, in particular dicotyledons such as cotton, rape, soya and sugar beet.

The active compound formulations of the formula I can be applied pre-emergence to sown areas of crop plants or are preferably applied post-emergence to said emerging crop plants as contact herbicides.

Thus, in soybean cultures, an excellent selective herbicidal action is achieved by the pre-emergence application of the compositions containing the active compound of the formula I.

Accordingly, the present invention also relates to herbicidal compositions and / or to plant growth control which contain a compound of the formula I as active substance, to the production of these compositions and to the use of such compositions or active ingredients for selectively controlling weeds in crop plants and / plant growth.

The active compound content of the commercially available preparations is between 0.1 and 95% by weight, preferably between 1 and 80% by weight. Depending on the circumstances, the application rates may be as high as 0.001 percent by weight.

The compositions according to the invention are prepared in a manner known per se by thoroughly mixing and grinding the active compounds of the formula I with suitable carriers and / or dispersants, optionally with the addition of inert anti-foaming agents, wetting agents, dispersing agents and / or solvents. The active substances may be high

Я Record and use in the following forms of processing:

solid forms of processing:

dusting, spreading, granulate, coated granulate, impregnated granulate and homogeneous granulate;

water-dispersible concentrates of the active substance:

wettable powder, paste, emulsion, emulsion concentrate;

Liquid processing:

solutions.

Emulsion concentrates are preferably used as processing forms.

Other biocidal active ingredients or compositions can be admixed with the compositions of the present invention. Thus, the novel compositions may contain, for example, insecticides, fungicides, bactericides, fungistatics, bacteriostats, nematicides or other herbicides in addition to the compounds of the general formula I to broaden the spectrum of activity.

The following examples serve to illustrate the invention in greater detail without restricting it in any way. Temperatures are given in degrees Celsius. Percentages and parts refer to weight. Unless otherwise indicated, the racemic mixture is meant when the active compound of the formula I is mentioned.

Examples illustrating the production of active ingredients:

Example 1

Preparation of N - [4- (3-chloro-5-trifluoromethylpyridyl-2-oxy) phenoxy] propionic acid acetone oximester

(a) Production of intermediate:

N- [4- (3-chloro-5-trifluoromethyl-pyridyl-2-oxy) -phenoxy] -propionic acid methyl ester

O-CH-COOCH.

g (0.27 mol) of α- (4-hydroxyphenoxy) propionic acid methyl ester and 47 g (0.34 mol) of potassium carbonate are stirred in 300 ml of ethyl methyl ketone for 1 hour at

4-40 ° C, then 2 g of benzyltriethylammonium chloride and 58.3 g (0.27 mol) of 2,3-dichloro-5-trifluoromethylpyridine are added and the reaction mixture is heated under reflux for 10 hours. The resulting salt was filtered off and the filtrate was evaporated. There was obtained 85.5 g (85% of theory) of N- [4- (3-chloro-5-trifluoromethyl-pyridyl-2-oxy) -phenoxy] -propionic acid methyl ester.

(b) Production of further intermediate:

N- [4- (3-chloro-5-trifluoromethylpyridyl-2-oxy) phenoxy] propionic acid

37.5 g of the ester produced according to a) are stirred in 120 ml of 2N sodium hydroxide solution for 2 hours at 4-70 ° C. After cooling to room temperature, the mixture was acidified with concentrated hydrochloric acid and extracted with diethyl ether.

The combined extracts were dried over magnesium sulfate, filtered, and the solvent removed in vacuo. 33 g (91.3% of theory) of [alpha] - [4- (3-chloro-5-trifluoromethyl-pyridyl-2-oxy) -phenoxy] -propionic acid, m.p. 104 DEG-106 DEG C., are obtained.

(c) Production of intermediate:

α- [4- (3-Chloro-5-trifluoromethyl-pyridyl-2-oxy) -phenoxy] -propionic acid chloride]

18.1 g (0.05 mol) of the acid produced according to b) and 15 ml of thionyl chloride are stirred at 4-60 ° C for 5 hours. Excess thionyl chloride was removed in vacuo, the residue was taken up in toluene and evaporated to dryness. 19.8 g of α- [4- (3-chloro-5-trifluoromethylpyridyl-2-oxy) phenoxy] propionic acid chloride are obtained in the form of a yellow oil.

(d) Production of the final product:

11.8 g (0.03 mol) of the acid chloride prepared in (c) are dissolved in 40 ml of toluene. A solution of 2.4 g (0.034 mol) of acetonoxime and 4 g (0.04 mol) of triethylamine is added dropwise at 0 ° C. The reaction mixture was stirred at room temperature for 2 hours, the precipitated salt was filtered off and the filtrate was evaporated. The residue was taken up in ethyl acetate / hexane (1: 1) and the solution was filtered through silica gel. 9.2 g (73% of theory) of acetone oximester α- [4- (3-chloro-5-trifluoromethyl-pyridyl-2-oxy) -phenoxy] -propionic acid, m.p.

The following compounds of formula I can be prepared in an analogous manner:

Table 1

Compounds of formula I:

compound number X Ri R2 physical constants 1 Cl H CH3 2 Cl CHs CH3 mp 59-62 ° C 3 Br CH3 CHa 4 Cl H C2H5 6 Cl C2H5 C2H5 n _D 25 = 1.5250 7 Cl CH3 (п) С ^; ^ Ы7 8 Cl CH3 C2H5 n _D 30 = 1.5220 9 Br (i) C3H7 (i) CsH7 11 Cl H C6H5 n _D 35 = 1.5620 13 Cl (n) CsH7 (n JC 3 H 7 14 Cl CH3 CeH5 16 Br CH3 C6H5 17 Cl CHs (n) C.HIg 18 Cl CH3 —CH = CH — CH3 19 Dec Cl CH3 —CH = C ((CH3) 2) 20 May H H terc.CaH9 21 H CHs CH3 ng30 = 1.5165 22nd H CH3 C2H5 nD 30 = 1.5135 23 H C2H5 C2H5 24 Cl - (CH 2) 14 - nD 30 = 1.5320 25 Cl - (CH2) 5- nD 25 = 1.5327 27 Mar: H - (CH 2) 4 - 28 F CH3 CH3 29 F CH3 C2H5 30 F C2H5 C2H5 31 Cl CHs C (CH 3) 3 32 Cl CHs CH2CH (CH312 Examples illustrating composition a preparing for For production: (b) 25%; and (c) 50% e- Wednesday of the mulz concentrate is used as follows- of cleaning substances: Example 2 Emulsion concentrate and) (b) whose

active ingredient of the formula I 10% 25% 50% calcium dodecylbenzenesulfonic acid 5% 3 0/0 4% castor oil polyethylene glycol ether (36 moles of ethylene oxide) 5% 7% tributylphenol polyethylene glycol ether (30 moles of ethylene oxide) 6% mineral oil with a high content of paraffin 10% - - cyclohexanone - —- 15% mixture of xylenes 70% 65% 25%

Emulsions of any desired concentration can be prepared from such concentrates by dilution with water.

The novel 4-pyridyloxyphenoxypropionic acids and their derivatives of the formula I, as well as the compositions containing them, have an excellent selective herbicidal activity against weeds in a wide variety of crop plants. Some of these substances also have the ability to control plant growth.

Although the new active compounds of the formula I are effective in pre-emergence and post-emergence application, unlike many of the known phenoxyphenoxy derivative herbicides, they have an excellent effect in pre-emergence application.

Preferably, the new active ingredients are formulated, for example, as 50% or 25% emulsifiable concentrates and these are diluted with water, in which case they are applied post-emergence to the crop stands or applied directly to the soil surface pre-emergence or incorporated into the soil.

The following tests serve to demonstrate the usefulness of the active compounds according to the invention as herbicides (applicable preemergence) and as plant growth inhibitors:

Example 1 a d 3,

Preemergence herbicidal effect

In the greenhouse, immediately after sowing the test plants in pots with a diameter of 11 cm, the soil surface is treated with an aqueous suspension of active substances obtained from 25% emulsion concentrate. Two different series of concentrations were used, corresponding to 1 and 0.5 kg of active substance per ha. The pots are then kept in a greenhouse at 22-25 ° C and 50-70% relative air humidity and evaluated after 3 weeks. The results are scored on the following scale from 1 to 9:

= plants do not germinate or are completely dead to 8 intermediate stages of damage = plants undamaged (as in untreated control).

The test results are summarized in the following table:

T compound no. application rate kg / ha 1 2 0.5 plant: And the fatua vena 2 2 Bromus tectorum 1 1 Lolium perenne 1 1 Alopecurus myosuroides 2 2 Digitaria sanguinalis 1 1 Echinochloa crus galii 1 1 Sorglium halepense 1 1 Rottboellia exaltata 1 1 soya 8 8 sugar beet 9 9 cotton 9 9

bulka

8 21 22nd 1 0.5 1 0.5 1 0.5 1 2 7 9 3 9 1 2 2 2 1 6 1 1 1 2 1 1 1 1 1 1 1 2 1 1 1 2 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9

Example 4

Herbicidal effect after application of active substances after emergence of plants (post-emergence application)

Various crops and weeds are grown in pots in a greenhouse from seed until the plant reaches 4-6 leaves. Thereafter, the plants are sprayed with an aqueous active substance emulsion, the application rate of active substance corresponding to 0.25 kg of active substance per ha. The treated plants are then maintained under optimal conditions of light, irrigation, temperature (22-25 ° C) and air humidity (50-70% relative humidity). 15 days after treatment, evaluation of the experiments according to the above scale is performed.

The results of this test are summarized in the table below:

Table compound number

21 22 plant:

Avena fatua1

Bromus tectorum2

Lolium perenne1

Alopecurus myosuroides1

Digitaria sanguinalis1

Echinochloa crus galii1

Sorghum halepense1

Rottboellia exaltata1 soya9 sugarbeet7 cotton9

Example · 5

Increase soybean yield

Plastic containers filled with a mixture of clay, peat and sand (6: 3: 1) are sown with "I-Iark" soybeans in an air-conditioned room. Under optimal conditions of temperature, illumination, fertilization and irrigation, after about 5 weeks, the plants could develop to a 5-6 leaf stage. At this stage, the plants were sprayed with an aqueous suspension of the active ingredient until the plants were wetted. The active compound concentrations are 10, 50, 100 and 500 ppm of active compound. The test is evaluated approximately 5 weeks after application.

Using compound 2, a slight decrease in the height of growth was achieved at concentrations of the active compound of 50 and 500 ppm compared to untreated control plants, while the seed load increased by about 4 to 7%.

Compound No. X

Example 6

Comparative example

In a greenhouse, the post-emergence experiment compares the selective herbicidal effect of the four compounds of this invention with a structurally similar compound known from U.S. Patent No. 4,200,587.

Test compounds:

a) according to the present invention

Ri

R2

Cl

Cl

Cl

Cl

CH3

C2H5 - (CH2) 4 - (CH2) 5 -

CH3

C2H5

(b) a compound known from U.S. Patent No. 4,200. 587

α- (p-trifluoromethylphenoxyphenoxy) propionic acid acetonyloxime ester (Example 3).

Postemergence experiment

Various crops and weeds are grown from potted seeds in a greenhouse until they reach the 4-6 leaf stage. Thereafter, the plants are sprayed with an aqueous emulsion of active ingredient in an amount corresponding to 0.5, 0.25, 0.125 kilograms per hectare, 60 g / ha and 30 g / ha. The treated plants are then maintained under optimal conditions of light, irrigation, temperature (22-25 ° C) and air humidity (50-70% relative humidity). 15 days after. treatment is evaluated and the results are evaluated according to the following scale:

= plants do not germinate or are totally dead to 8 ==. intermediate damage - plants are undamaged (as in the case of untreated control).

The test results are summarized in the table below:

со о со о со от см о от см о о ОТ со со о со от см

от см о о от отот> соотсмсосог> .отот) от

ОТОСОСОгЧгЧСОСООТОТОТ

CM Ф М М CM CM CM CM CM CM CM CM CM CM CM Ч CM Ч от от от от от от от от от от от от от от от от от от от от.. от от от

ОТСЛФО ^ СМСОСОФСЛОТОТ

СМСМСМСМгЧгЧСМСМОТОТОТ гЧСМгЧСМгЧгЧгЧгЧОТОТОТ гЧСМгЧгЧгЧгЧт-Чт-ЧОТОТЬ *

ОТ см о со о со от см о

LO см о о о о со о СО ф

™ от см о от см о о от

Honor 'ož

ОТОТСОСОСМ1 / .ФСООТОТОТ

СЛОЭООТСМСМСМФОТОТОТ

СОООСМСМтЧгЧгЧСМОТОТОТ гЧСОСМгЧгЧгЧгЧгЧОТОТОТ гЧСМгЧгЧгЧгЧгЧгЧОТОТОО от ОТ со о 1> от ОТ ОТ

ОТОТ’Ф ^ СМСМСОСООТОТОТ

СМ СО СМ СМ Ч м м от М М — I т-Ч гЧ т — I г — I гЧ ОТ) ОТ) i — I СМ гЧ r-Ι гЧ т — I т — I т— I от от со

WITH

о)

Honors я

CD

0. α φ

honors P

6

P чф сл

S о f4 DQ

Рч p .2

Q honors a Ф> ϊ-4 a and t-l Й> O 3 Я сл CD rP

сл Рч

Ό

Y7 compound no.

quantity used g / ha 500 250

AND

125 60 30 plant

Avena fatua Bromus tecto- 2 7 rum 4 4 Lolium Perenne Alopecurus 2 4 myosuroides Digitaria san- 2 3 guinalis Echinochloa 1 1 Crus galii Sorghum hale- 1 1 pense Rottboellia 1 1 exaltata 1 1 soya 7 9 sugar beet 9 9 cotton 9 9 Conclusion

The compounds of the invention have the ability to control grass weeds in soybean, cotton and sugarbeet cultures with a certain application rate of 60 to 125 g / ha.

The known compound exhibits a similar effect. Avena fatua, Bromus tectorum

99

99

99

99

24

138

55

39

99

99

99

However, Lolium perenne and Alopecurs myosuroides are only reliably combated at 250 and 500 g / ha application rates.

In order to achieve the same selective herbicidal effect in the above cultures as with the compounds according to the invention, a much higher application rate of the known compound is required than the compounds according to the invention.

Claims (8)

A herbicidal and / or plant growth regulating agent, characterized in that it contains at least one pyridyloxyphenoxypropionic acid derivative of the general formula I as an active ingredient. CH. i ^J O-CH-COON = N / In which X is hydrogen or halogen, R 1 is hydrogen or C 1 -C 6 alkyl, R 2 is C 1 -C 6 alkyl, C 3 -C 4 alkenyl or phenyl; or R 1 and R 2 together are also tetramethylene or pentamethylene. 2. A composition according to claim 1, wherein the active ingredient comprises at least one compound of formula I wherein X is chlorine or bromine and R1 and R2 are as defined in 1. 3. A composition according to claim 1, wherein the active ingredient comprises at least one compound of formula I wherein X is hydrogen and R1 and R2 are as defined in 1. 4. A composition according to claim 1, wherein the active ingredient is at least one compound of formula (I) wherein X is chlorine, R1 is hydrogen or (C1-C3) alkyl and R2 is (C1-C3) alkyl. carbon atoms. 5. A composition according to claim 1, wherein the active ingredient is [alpha] - [4- (3-chloro-5-trifluoromethylpyridyl-2-oxy) phenoxy] propionic acid acetoxime ester. 6. A composition according to claim 1, wherein the active ingredient is [alpha] - [4- (3-chloro-5-trifluoromethylpyridyl-2-oxy) phenoxy] propionic acid methyl ethyl ketone oxime ester. 7. A composition according to claim 1, wherein the active ingredient is [alpha] - [4- (3-chloro-5-trifluoromethylpyridyl-2-oxy) phenoxy] propionic acid diethyl ketone oxime ester. 8. A process for the preparation of an active ingredient according to claim 1, which is reacted in an organic solvent which is inert to the reactants at atmospheric pressure and at a temperature between -5 DEG C. and 200 DEG C. and optionally in the presence of an equimolar amount of an inorganic or organic base as an acid-binding agent, an acid halide of formula II wherein: X is as defined above and Hal is a halogen atom, with an equimolar amount of the oxime of formula III \ HO-N = t in which R 1 and R 2 are as defined above.